1. Field of the Invention
The invention relates to a rotor for a comminution machine according to the preamble of claim 1, which includes several disks which are non-rotatably secured on a shaft, rotatable hammers distributed between the disks, and protective caps covering the rotor to protect against wear.
2. Description of the Related Art
Rotors of this type are known from DE 26 05 751 A1, with modifications disclosed in DE 43 43 801 A1 so as to form a wear part system. A closer examination of the role played by protective caps covering the rotor against wear reveals that the outer protective caps, which cover the outer disks of the rotor, are of particular importance in the rotor system, both as a tool as well as to protect the comminution machine system. Although the outer protective caps, like the other protective caps, can be categorized initially as inactive wear parts, they have to perform additional functions due to the particular forces they are subjected to. Until now, the outer protective caps were secured rather loosely above the hammer axis against the effect produced by centrifugal forces and by external forces pointing in the radial direction. A prior art element, a so-called locking dog, which is secured on the outer disks, fixes the position of the hammer axis and, at the same time, covers the web of the protective cap which projects over the disk. Although in practical applications, this constructive solution withstood the rigors of the comminution process, the forces and the torque exerted by the hammer and the hammer axis on the closing element and the cap created problems which can in the end lead to extensive damage.
GB 2 143 748 A2 discloses a rotor for a comminution machine with several disks which are non-rotatably secured to a shaft, and hammers distributed between the disks, wherein the hammers are rotatably supported on hammer axes which extend through the disks and are parallel and eccentric with respect to the shaft. At least the protective caps which cover the components of the rotor exposed to secondary wear, have elements formed as segments of a circular arc, with the bearing hub of the protective caps attached between the disks on the hammer axes. The rotor with the protective caps, wherein the elements of the protective caps are in the form of a segment of a circular arc, forms a substantially cylindrical jacket with openings which are mutually offset in a predetermined fashion so that the hammers can swing through and the outer protective caps are decoupled from the forces of the hammers and the hammer axes. A locking dog which is directly attached to the end disks, limits and secures the actual position of the respective hammer axis on the end disk.
In addition, U.S. Pat. No. 4,222,530 discloses that the protective caps covering the outer disks of the rotor are decoupled from the forces of the hammers and the hammer axes and from the forces exerted directly by the hammers on the outer protective caps, wherein the protective caps encompass the disk and are secured on the disk for force transmission by at least one connecting element.
In spite of the decoupling of the forces, as described above, the construction of the aforedescribed rotors is complex and therefore expensive.
It is a object of the invention to provide a rotor for a comminution machine with several disks which are non-rotatably secured on a shaft, and with hammers distributed between the disks, wherein the hammers are rotatably supported on hammer axes which extend through the disks and are parallel and eccentric with respect to the shaft. At least the parts of the rotor subjected to the secondary wear include protective caps having elements formed as segments of a circular arc, wherein the bearing hubs of the protective caps are secured between the disks the hammer axes. The rotor, by way of the protective caps having elements formed as segments of a circular arc, forms a substantially cylindrical jacket with openings which are mutually offset in a predetermined manner, allowing the hammers to swing through. The outer protective caps are decoupled from the forces produced by the hammers and the hammer axes. A locking dog which is attached directly to the end disks, limits and secures the axial position of the respective hammer axis on the end disk. The outer protective caps can be attached to the disks in a simple manner, which saves material and costs.
Unlike in the present state of the technology as disclosed in U.S. Pat. No. 4,222,530 the protective caps of the present invention covering the outer disks of the rotor are decoupled from the forces produced by the hammer axes and from the forces exerted by the hammers directly on the outer protective caps. This is accomplished by having the outer protective caps, which are exposed to the lateral forces of the hammers, simultaneously encompass with their respective web the outer edge of the disks, and with a projection formed as a circular segment a shoulder of the disk. The outer protective caps are formfittingly attached to the disk by at least one connecting element, such as a hexagon socket screw. On the other hand, the outer protective caps abutting the inner protective caps are secured to the outer disk in force-transmitting arrangement by at least one connecting element, such as a hexagon socket screw. A locking dog which is also attached directly to the disk, secures and limits the axial position of the respective hammer axis on the disk.
With this arrangement according to the object of the invention, the outer protective caps which are subjected to the lateral forces of the hammers, are no longer exposed to the additional forces of the hammer axes experienced with prior arrangements and are therefore securely and formfittingly connected. The hammer axes are secured only by the locking dogs. The outer protective caps abutting the inner protective caps, where only a minimal force is transmitted from the inner protective cap to the outer protective cap, have an adequate force-transmitting connection.
Surprisingly, it has been observed that the improved force decoupling according to the invention has not only constructive and technological advantages for the manufacturer, but has also technological advantages for the operator, and eliminates breakage altogether.
As a further advantage, costs associated with maintaining a parts inventory can be reduced by storing the replacement parts according to the invention and also due to the improved maintenance intervals.
These advantageous effects support additional features of the invention, in that the outer surface of the disk can be made substantially planar by providing the webs of the outer protective caps with recesses which at least partially encompass the locking dogs. In a further improvement, the webs and the locking dogs have in their respective contours similar recesses located on the outside of the disk, thereby eliminating any projecting parts. This is achieved by attaching to a planar disk another disk with peripheral contours which essentially follow the tangential contours of the webs and the locking dogs, wherein these contours have openings facing the disk, with the locking dogs and the webs inserted in the openings to form a substantially planar surface.
It is advantageous for rotors subjected to excessive wear, if the respective web of the edge protection caps which are subjected to the lateral forces of the hammers, is formfittingly attached to the end disk through at least one attachment element, such as a hexagon socket screw, with the head of the screw resting on the threaded bore in the end disk, wherein a play exists between the head and the flange-like shoulder of the head and the respective stepped bore in the web.
Conversely, the webs of the protective caps, which abut the inner protective caps, are secured for force transmission using the attachment elements, such as hexagon socket screws, by having the flange-like shoulder of the head rest on the respective stepped bore in the web.
To protect the inner sides of the attachment elements, such as the hexagon socket screws, from becoming deformed by the wear process, connecting elements, preferably cap nuts, are inserted from the inner side and are secured either formfittingly or for force transmission, with the surface of the cap nut being flush with the inner surface of the disk.
The combined design and functionality of the characteristic features of the invention provides a rotor of a significantly improved design and other technical advantages, both in manufacturing and applications.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are intended solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims.